Horizontal fin for beam plate



Unit d SQWSPQEfl Qfiic 2,722,619 I Patented Nov. 1, 1955 2,722,619 HORIZONTAL FIN FOR BEAM PLATE I Application April 6, 1953, Serial No. 346,876

4 Claims. (Cl. 313-69) This invention relates to radio tube construction.

In particular it relates to beam power tubes which employ multiple grids and wherein it is essential that the turns of the grids on each side of the cathode be laterally aligned with the turns of the inner control grid shielding the turns of an outer grid to permit free flow of electrons in sheet-like form from the cathode to the anode.

In such tubes it is the practice to employ beam confining plates at the wire supported sides of the grids. These plates in the past have been supported in the top and bottom insulating members which support the other elements of the tubes. To further reinforce the beam confining plates the top and bottom of the plates had been reinforced by making both plates of one piece with a window cut out of one face of the piece, for passage therethrough of the electrons, leaving top and bottom bars in the plane of the window for reinforcing purposes. However, in such a construction, due to the height of the anode, it is impossible to inspect the grid Wires of the several grids to see whether the Wires of one grid are in lateral alignment with the wires of another grid. For best performance and maximum compactness it is not desirable to cut down the vertical size of the anode relative to the vertical length of grids nor increase the height of the beam confining structure and grids.

It is an object of this invention to provide means whereby a one piece beam confining structure may have the height of its window enlarged sufiiciently to permit observation of the alignment of the grid wires and yet retain the rigidity of the structure.

It is another object of the invention to provide better reinforcement of the beam confining structure than has been accomplished in the past.

For a full description of the construction adopted to facilitate inspection of grid wire alignment, attention is directed to the following description and accompanying drawings in which Fig. 1 shows in side elevation a portion of the mount of a power tube, the anode being broken away to disclose the beam plate more clearly.

Fig. 2 is a cross-sectional view through the tube mount taken on line 22 of Fig. 1.

Fig. 3 is a perspective view of my new beam confining plate structure and Fig. 4 is a view of the blank employed to manufacture the structure of Fig. 3.

Referring to the drawing more in detail, 10 is a portion of the mount in which there is a bottom insulating support or mica 12, anode support rods 14, beam confining plate structure 16, screen grid support rods 18, control grid support rods 20, cathode 22 within which there is a filament and top insulating support or mica 23, all, except for the beam confining plate structure, being old in the art. The cathode is much narrower than the width of the control grid, leaving exposed for through-vision the grid wires to the sides of the cathode.

The beam confining plate 16 comprises a parallelepiped open at top and bottom and it is provided with tabs 24 which are inserted through suitable punched holes in the micas to .be bent over thereagainst. The platestructure has two vertical edges 26 providing a space therebetween substantially the width of the control grid for the unrestricted flow of electrons fromthe cathode, between the control grid wires 28 and the screen grid wires 30 to the anode 32. The parallel face 34 of the plate structure has vertical edges 36 providing a space between these edges equal in width and height to the space between the edges 26. However, to provide a rugged construction, the two parts of the structure are joined by two fins 38 and 40 substantially perpendicular to the adjoining face of the parallelepiped. The upper fin 38 has a trough 42 therein providing a reinforcing corrugation and an upper face which may lie fiat against the bottom surface of the upper insulating member and the lower fin 40 has a reinforcing corrugation 44 with the trough facing downwardly so that the lower face of the fin may lie flat against the upper face of the lower insulating member. The fins extend from side to side of the plate structure forming an etficient reinforcing means therefor, yet at the same time providing ample unobstructed view of the grid wires sufiicient to determine whether lateral alignment exists.

The plate structure is made still more rugged by providing the same with lateral corrugations 46 and, for a similar purpose, the anode is provided with both vertical and lateral corrugations 48.

The beam confining plate may be formed by first stamping out a blank as shown in Fig. 4 and then bending the same and forming the fins and corrugations as shown in Fig. 3. While I have shown a specific form of fin, it should be obvious that the fins may be flat so long as they are at an angle to the plane of the plate and they need not necessarily be at a right angle to the plane of the window, all without departing from the spirit of the invention.

What I claim is:

1. A tube construction comprising a cathode, a control grid surrounding the cathode, a screen grid surrounding the control grid, the wires of said control grid shielding the wires of the screen grid, a beam confining plate structure having the form of a parallelepiped surrounding the grids but having openings on opposite faces of the structure exposing the grid wires, an anode surrounding the assembly, the opening on one side of the plate structure being effected by spacing apart lateral edges of the plate structure and the opening on the other side being a window of a height at least equal in height to the opening on the first side, at least one of the upper and lower boundaries of the window being defined by a fin extending substantially perpendicular to the adjacent face of the structure and positioned at the edge of the structure, the opening and window being of a height slightly greater than the height of the anode and the grid winding being of a length to at least fill the height of the window whereby with the anode positioned so that an edge is vertically displaced from the fin, inspection of alignment of the grid wires is possible.

2. A beam confining plate structure comprising a plate in parallelepiped form with open top and bottom ends and having two wide parallel sides and two narrow parallel sides, one of the Wide sides having an opening between two laterally spaced edges of the plate, the other of the wide sides having a window in opposition to the opening, at least one of the upper and lower boundaries of the window being defined by a fin projecting substantially at right angles to the plate structure.

3. A beam confining plate structure comprising a plate in parallelepiped form with open top and bottom ends and having two wide parallel sides and two narrow parallel sides, one of the wide sides having an opening between two laterally spaced edges of the plate, the other of the wide sides having a window in opposition to the opening, at least one of the upper and lower boundaries of the window being defined by a fin projecting substantially at right angles to the plate structure, said fin extending in a direction outwardly of the parallelepiped.

4. A beam confining plate structure comprising a plate in parallelepiped form with open top and bottom ends and having two wide parallel sides and two narrow parallel sides, one of the wide sides having an opening between two laterally spaced edges of the plate, the other of the wide sides having a Window in opposition to the 4, opening, the upper and lower boundaries of the window being defined by fins projecting substantially at right angles to the plate structure, said fins extending in a direction outwardly of the parallelepiped.

References Cited in the file of this patent UNITED STATES PATENTS 2,459,072 Haines Jan. 11, 1949 2,487,592 Rishell Nov. 8, 1949 2,573,397 Burnside Oct. 30, 1954 

